1. Field of the Invention
The invention relates to a device for joining material webs during the operation of a web-fed rotary press and, more particularly, to an emergency material web-joining device which is activated when a paper web becomes broken or torn during the operation of a rotary printing press.
The published European Patent Document EP 0 654 433 A1 describes a device for preventing damage when material webs become broken or torn in a rotary printing press. With a device of this type, it is possible, through the use of control clutches, to prevent damage caused by the torn or broken webs to production devices, including rotating cylinders, such as printing blanket cylinders of the rotary printing press. According to the teaching of this document, the paper web runs partly around a rotatably mounted guide roll, and rollers are provided to clamp the web to this roll, which is controlled in the paper web travel direction by a control clutch.
With this heretofore known device, the cylinders of the printing unit can be protected effectively if a web should tear or break; however, the torn or broken web can slide out unimpeded from a cooling roll section arranged downstream of the dryer or can run out of a superstructure of turner or angle bars.
2. Summary of the Invention:
It is accordingly an object of the invention to provide a device for joining material webs during the operation of a web-fed rotary press, the device being a new emergency device wherein, following a paper web break or tear in a printing press, it is possible to maintain the travel of a paper web which has been threaded into components of the rotary printing press.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an emergency web-joining device activatable when a break occurs in a paper web disposed in operating condition in a rotary printing press, comprising an unwinder having a paper web supply wound thereon, the unwinder being disposed in the vicinity of a roll for guiding a previously printed paper web, the supply of paper web and the previously printed paper web being joinable to one another in order to maintain passage of the previously printed web through a press part located downstream of the unwinder.
In accordance with another feature of the invention, the unwinder is disposed in relation to the printed paper web in a manner that the paper web supply and the printed paper web are supportable on one another.
In accordance with a further feature of the invention, the unwinder is mounted in a pivotable holder.
In accordance with an added feature of the invention, the web-joining device includes a positioning element for bracing the paper web supply on the printed paper web.
In accordance with an additional feature of the invention, the positioning element is a cylinder controllable by a pressure medium.
In accordance with a particular feature of the invention, the cylinder is controllable pneumatically.
In accordance with an alternative feature of the invention, the cylinder is controllable hydraulically.
In accordance with yet another feature of the invention, the unwinder occupies a position sideways from the printed paper web and is mounted at a smallest possible distance therefrom.
In accordance with yet a further feature of the invention, the paper web supply is provided with adhesive at locations on a side thereof facing towards the printed paper web.
In accordance with yet an added feature of the invention, the locations at which the adhesive is provided are spaced apart from one another over the width of the paper web supply.
In accordance with yet an additional feature of the invention, the adhesive is located substantially in a central part of the paper web supply, the central part being disposed beyond the paper web supply wound on said winder.
In accordance with another feature of the invention, the web-joining device includes a drive assigned to the unwinder for accelerating the paper web supply wound thereon.
In accordance with a further feature of the invention, the drive engages with the outer circumferential surface of the paper web supply wound on the unwinder.
In accordance with an alternative feature of the invention, the drive engages directly with a spindle of the unwinder.
In accordance with another aspect of the invention, there is provided in a rotary printing press having a cooler including a group of cooling rolls, a web-joining device positioned in the group of cooling rolls, the unwinder of the web-joining device being disposed in the vicinity of one of the cooling rolls so as to maintain free passage of the paper web in and downstream of the cooler.
In accordance with a further aspect of the invention, there is provided in a rotary printing press having a superstructure of turner bars, a web-joining device positioned in the superstructure of turner bars, the unwinder of the web-joining device being disposed in the vicinity of one of the turner bars so as to maintain free passage of the paper web in and downstream of the superstructure.
In accordance with a concomitant aspect of the invention, there is provided in a rotary printing press having a folding machine, a web-joining device positioned in the folding machine, the unwinder of the web-joining device being arranged in the vicinity of a roll disposed on the folding machine so as to maintain free passage of the paper web in and downstream of the folding machine.
A particular advantage of the invention is that, upon the occurrence of a sudden paper web break in the press, a part of the web that is to be processed in the press can remain in the threaded state, in particular, that part of the web which is located in the regions that are most difficult to attain access to from the outside. By extremely rapid positioning of the unwinder in the ready-to-use position in the press, which is braked upon the occurrence of a web break, it is possible to employ the idling operation of the rotating press, which at most lasts only a few seconds, so as to join the supply web to the previously printed web. During the idling operation of the rotating press, the joined webs, namely the previously printed web and the unprinted web, are guided through the components of the press, such as the cooling roll section, the superstructure of turner bars and the former of the folding machine, so that the paper web can continue to be guided through these components. The passageway or travel path of the paper web, at least in one part of the press, is thus saved, and the press can be restarted and run up to operating speed very rapidly.
According to further features of the emergency web-joining device of the invention, the unwinder is positioned in relation to the printed paper web in such a manner that the supply paper web and the printed paper web can, if necessary, be supported or braced on one another, and the web can run through unimpeded during normal operation. The unwinder can be mounted on a pivotable holder, and the paper web supply can be brought into contact with the paper web running through the use of a positioning element. The positioning element may be formed as a cylinder controllable by a pressure medium. When not in operation, the unwinder is disposed at a smallest possible distance from the travel or passage plane of the printed web, in order to ensure rapid joining of the supply web and the printed web part, which runs by in the region wherein the unwinder is disposed. The travel distance required for the positioning of the paper web supply into the ready-to-use position is thus extremely short. The paper web supply is provided with adhesive, such as adhesive tapes or the like, on the side thereof facing towards the printed paper web. The adhesive may be applied at locations spaced from one another over the width of the supply paper web, or centrally and along the travel direction of the web.
The speed of the unwinder, which is provided with the supply paper web, is accelerated to the speed of the press and maintained thereat by a control which is assigned to the unwinder, so as to ensure the smoothest possible joining of the unprinted supply paper web to the printed paper web in the event of a break in the latter. The control can engage with the outer circumference of the wound-up supply web with the aid of a drive belt; equally well, the control can act directly upon the spindle of the unwinder. Both forms of controls are constructed for matching the rotational speed, in order to compensate for the change in diameter of the wound-up supply web on the unwinder.
The emergency web-joining device can advantageously be positioned at the exit from the dryer, i.e., in the cooling roll unit, or at the entry to the superstructure of turner bars of the rotary printing press. It may otherwise be disposed at the exit from this superstructure, above the first longitudinal folding device of the folding machine, or in the interior of the latter.
The unwinder of the emergency web-joining device can be positioned in the vicinity of one of the cooling rolls, in order to maintain the passage of the paper web within and downstream from the cooler or, viewed more generally, above the cut-off roll at the entry to the superstructure of turner bars.
The unwinder of the emergency web-joining device can likewise be positioned in the vicinity of a turner bar, in order to preserve the passageway for the paper web in the event of a web break in and downstream of the superstructure of turner bars. Furthermore, the unwinder of the emergency web-joining device can be arranged in the vicinity of a roll that is mounted on the folding machine, in order to keep free the passageway for the paper web in and downstream of the folding machine.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for joining material webs during the operation of a web-fed rotary press, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: